1. Field of the Invention
The present invention relates to a fuel injection control device for an engine. More particularly, the present invention relates to a fuel injection control device for an engine having a pressure accumulator section provided in a fuel supply passage and a fuel injector connected to the pressure accumulator section, the engine being configured to execute a plurality of fuel injections per cycle.
2. Background Information
There are known engine fuel supply systems that employ a common rail as a pressure accumulator section in the fuel supply passage and supply fuel to the fuel injectors installed on the cylinders from the accumulator section. A known method of controlling the fuel injection of such a common rail type fuel supply system is to precede a main fuel injection that serves to develop the output power of the engine with a pilot fuel injection that serves to suppress the generation of nitrogen oxides (NOx). When such a control method is used, the total injection quantity delivered by the two fuel injections is generally adjusted in accordance with the pressure that exists inside the accumulator section before the pilot injection is executed. The pilot injection is a small-quantity injection executed during the compression stroke before the main injection and serves to suppress the generation of NOx by reducing the ratio of premixed combustion.
A related technology for accurately controlling the fuel injection quantity in a common rail type fuel supply system is disclosed in Japanese Laid-Open Patent Publication No. 2001-082223 (paragraph 0022). The technology of this publication is configured to detect the pressure inside the accumulator section before and after the fuel is injected, and then calculates the actual fuel injection quantity based on the difference between the detected pressures. It then compares the calculated fuel injection quantity to a target fuel injection quantity determined based on the operating state of the engine and adjusts the injector operation command value accordingly.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved fuel injection control device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.